1. Field of the Invention
The present invention relates generally to window blind assemblies and, more particularly, to such a window blind assembly, which has a detachable control system.
2. Description of the Related Art
The control system of a regular Venetian blind includes two parts, the lifting control unit and the slat tilting control unit. According to early blind designs, the lifting control unit comprises lift cords extended to the outside for operation by the user. However, because the exposed portions of the lift cords may be hung on the body of a person accidentally, causing death. In order to eliminate this problem, a rotary driving bar is disclosed to match with a transmission mechanism for lifting control instead of conventional lift cords. It is also well known to use a rotary driving rod for controlling the tilting angle of blind slats. In general, a rotary driving rod may be used in a window blind assembly to separately or concomitantly control the lifting of the blind and the tilting of the slats, thereby changing the light shading status of the window blind assembly.
There is known a detachable design of rotary driving rod for use in a window blind assembly to separately or concomitantly control the lifting of the blind and the tilting of the slats. According to this design, the user must prepare a special place to keep the detached rotary driving rod after each use. German Patent No. DE 19807050 A1 discloses a window blind control structure in which the rotary driving rod (2a) is equipped with a steel ball mechanism (7) detachably coupled to a coupling groove (4) in the transmission shaft (1) of the window blind assembly. It is to be noted that the reference numerals recited in this paragraph are directly derived from the German Patent No. DE 19807050 A1. By means of applying a force to the rotary driving rod (2a) in a particular direction, the rotary driving rod (2a) can easily be detached from the transmission shaft (1) of the window blind assembly for use to drive the transmission shaft of another window blind assembly. The design is practical in use. However, the complicated steel ball structure greatly increases the material and assembly costs of the control system.
It is the primary object of the present invention to provide a window blind assembly, which comprises a detachable control system.
It is another object of the present invention to provide a detachable control system for window blind assembly, which is inexpensive to manufacture.
To achieve these objects of the present invention, the window blind assembly comprises a headrail, a blind unit having slats and a bottom rail and suspended from the headrail, and a control system for regulating light-shading status of the blind unit. The control system comprises a transmission mechanism mounted in the headrail, and a driving device. The transmission mechanism has a force receiving member that is provided with a receiving portion, and actuating means rotatable by the force receiving member to change the light-shading status of the blind unit. The driving device has a handle for operation by the user, and a force output member detachably connected to the receiving portion of the force receiving member of the transmission mechanism. The receiving portion of the force receiving member is a rod member having a coupling groove extended around a periphery near a bottom end thereof. The force output member of the driving device has a receptacle connectable to the bottom end of the receiving portion of the force receiving member. The receptacle has at least one spring arm, each spring arm having a protruding engagement portion projecting in direction toward a central axis of the receptacle for engaging the coupling groove of the receiving portion of the force receiving member upon connection of the receptacle to the receiving portion of the force receiving member.
FIG. 1 is a schematic drawing showing the basic structure of a window blind assembly constructed according to a preferred embodiment of the present invention.
FIG. 2 is a sectional front view, in an enlarged scale, of the control system used in the window blind assembly shown in FIG. 1.
FIG. 3 is a right side view, partially in section of the control system according to the present invention.
FIG. 4 is a sectional front view of the control system according to another preferred embodiment of the present invention.